Nuns have always been a source of easy humor. Nunsense? The Singing Nun? "The Flying Nun"? "Catholic vaudeville," as actress Julia Sweeney labelled it in her one-woman show, God Said 'Ha!'. But Late Nite Catechism earns its belly laughs with the affectionate humor of recognition. The interactive one-person comedy, which began in Chicago at the Ivanhoe Theatre four years ago before branching out to Boston and now New York, takes the form of an adult instruction class about Catholicism in which a no nonsense nun asks questions of the audience, upbraids those who misbehave, tells some of the more colorful stories from the lives of the Saints, and tries to make sense of the some of the contradictory doctrines issuing from Rome.

So what's so funny about this play written by Vicki Quade and Maripat Donovan? For Catholics, much of it stems from the emotional regression that takes place when they are re-immersed in an environment that takes them back to a pre-pubescent age when nuns walked softly and carried a big ruler. For example, take the moment in the show when Sister asks how many in the audience may have gotten whacked by a ruler when they were attending parochial school. That brings up a number of hands and some interesting, often hilarious, stories as to why. The actress playing Sister improvises the rest.

"It's all the goofy stuff nuns told us to keep us in line because they had 52 kids in one class to control," said Donovan, who is playing Sister in the New York production and who performed in an improvisation group, People with Good Phone Manners in her native Chicago. "But the intent from the beginning was to show a real nun, not some helpless, dizzy thing who can't cope in the world as nuns are so often portrayed. Nuns are very capable women -- they run corporations, colleges, hospitals."

Donovan says that what she and her fellow nuns -- Mary Zentmyer in Chicago, Patti Hannon in Boston -- tap in the audience are memories which invariably lead them to act out in the interactive comedy. "If you were the class clown, you become the class clown; if you were shy and quiet, you become withdrawn; if you were the smart kid that knew everything, you want to answer every question," she says. Yet the show never spirals out of control although it may some times threaten to. "Nuns know how to keep control," she says.

The show has been such an audience pleaser since its inception that the producers, a Rhode-Island based company called Entertainment Events, are planning productions in Philadelphia, Toronto, Dublin and Sydney, Australia. (A version of the show ran in Melbourne for a year). Donovan says that while the show may resonate most personally with Catholics, it has been universally enjoyed by people of all denominations. The most free-wheeling part of the evening comes in the second half of the evening when Sister asks the audience if they have any questions. At a recent performance in New York, someone asked why the Catholic Church was so adamantly opposed to women priests? Donovan patiently explained that Pope John Paul II had just recently reiterated that opposition in a recent document, called a Papal Bull, arguing it on the basis of scriptural and traditional authority. "However, there is a group of Catholics which formed an organization to lobby for female ordination," she said. "It's called Committee for the Ordination of Women-or COW. And COW was really angry about that Papal Bull." All true.